The present invention relates to retrieving attribute information about an object represented in image information, more particularly, geographic information.
There is prior art for displaying geographic (map) information and attribute information about individual objects contained in the map when there is correspondence therebetween, choosing an object in the geographic information, and retrieving attribute information corresponding to the chosen object. For example, the local-government map system, "ARISTOWN", which is described in PIXEL (No. 56, pp. 73-78) is for framing a policy by using a map and administrative information, which is road information and ground information, together. This system provides connection between geographic information represented by vectors and descriptive data (attribute information). Features of the system are the retrieval of an administrative file on the basis of correspondence information between the administrative file and a map database for the computer processing of maps.
In the above-mentioned prior art, if attribute information is to be retrieved on the basis of the shapes or positional relations of objects present on displayed geographic information, a vector map which represents the objects by using vectors is prepared in advance, and, in addition, a correspondence which links the vector map and the descriptive data (attribute information) to each other is input. For this reason, to retrieve attribute information by using a map, first of all, it is necessary to prepare a vector map and input a correspondence. This work leads to the problems of consumed time and high cost.
To solve these problems, it has been considered to use an image map instead of the vector map. One example of correspondence information between image information, such as drawings or maps, and attribute information associated with the image information is introduced in "SCI' 93", the proceedings of the thirty-seventh, research-supporting lecture meeting held by the Institute of Systems' Control and Information Engineers, pp. 275-276, 1993. This publication discloses the preparation of link data for linking text DB information to image information. In the publication, map information is one example of image information and it is proposed to increase the efficiency of linking objects displayed on an image map to descriptive data (attributes).